A spinal tap is a procedure which takes samples of a patient's cerebrospinal fluid (CSF). Spinal taps are performed when the physician suspects that the patient may have bleeding (such as subarachnoid hemorrhage) or an infection of the central nervous system (such as meningitis or encephalitis). These procedures are often performed in the emergency room but are also performed in a doctor's office or in a hospital setting.
Usually, before beginning a spinal tap procedure, the physician, or another medical professional arranges the contents of a spinal tap “kit” on a tray, positioned next to where the physician will be sitting to perform the procedure. The “kit” usually consists of four sterile tubes, a spinal needle (with a stylet inserted through the spinal needle), along with items for sterilizing the patient's skin and draping the patient. Sometimes a test tube rack to hold the tubes is also positioned on the tray. Before the procedure, the physician or another medical professional removes all of these items from their sterile packaging, unscrews the caps from the tubes, and arranges everything on the tray for easy access during the procedure.
Usually, the patient is asked to lie down in a curled-up position, exposing the back. The physician then sterilizes the patient's back and numbs the skin around the insertion point. In other words, the physician or other medical professional does a “sterile prep and drape.” The physician then inserts a spinal needle, with a stylet inside the spinal needle, between the patient's vertebrae (usually in the L3-4 or L4-5 interspace) and advances the needle until the needle has reached the fluid-filled area surrounding the patient's spine, the dural space. The stylet is used to prevent the tip of the spinal needle from becoming blocked by tissue as the needle is inserted through the patient's skin and other tissues. Once the needle is in place, the stylet is removed from the spinal needle and usually placed on the sterile tray. CSF flows through the needle and drips from the proximal end of the needle. The physician then takes four sterile tubes (three for pediatric patients) in turn from the tray and fills the tubes each with approximately 1 ml (or 1 cc) of CSF.
Usually, the physician must reach for a (closed or open) tube on the tray, collect an appropriate amount of CSF in the tube, seal the cap onto the tube (so that the fluid does not spill), reach over to the tray, lay the tube down on the tray, pick up another tube from the tray and repeat the process. If the physician is using a test tube rack, the physician must take an open tube from the test tube rack, collect an appropriate amount of CSF in the tube, replace the tube into the test tube rack on the tray, pick the next open tube from the test tube rack, and repeat the process. Currently, each test tube itself must be held beneath the proximal end of a spinal needle as the spinal fluid is collected. Space is tight between the physician and the patient with a spinal needle protruding from his/her back.
Once collected, CSF is then sent to a laboratory to determine if the patient is suffering from viral (for example, Enteroviruses and Herpes viruses, as well as Arboviruses, Rabies or measles among other viral agents), bacterial (including Haemophilus influenza, Streptococcus pneumoniae, Neisseria meningitidis, and also Listeria monocytogenes, Staphylococcus epidermidis, Staphylococcus aureus, Mycobacterium tuberculosis, Escherichia Coli or other Gram negative enteric bacteria) or fungal (including Cryptococcus neoformans, Coccidioides immiitis, among other fungal agents) infection of the brain or supporting structures, among other possible diagnoses. The CSF is also, examined for white and red blood counts and chemical components.
This procedure is very uncomfortable for the patient. The procedure is especially uncomfortable if the patient is very young or very sick, which is often the case. Reducing the duration of this procedure would reduce the duration of the patient's discomfort. This procedure also represents significant risk to the patient. Time is ticking while the physician puts the stylet down on the tray, reaches for a test tube, places the test tube in the proper position to collect CSF, fills the tube, screws the cap back on and reaches for the next tube. All the while, CSF is flowing from the patient. Patients may develop severe side effects from the loss of too much CSF, including severe headaches. The risk of the patient moving and causing injury exists for the duration of the procedure. These risks include a risk of lacerating a spinal nerve, lacerating the meninges (causing permanent or persistent leaks of CSF), or bleeding, which complicates the interpretation of laboratory results. These risks are increased in very young patients who are more likely to move during the procedure. In addition, there is a risk of respiratory arrest in neonates who are held in a curled-up position for the duration of the procedure. Reducing the duration of this procedure reduces these risks. In addition, these procedures are often performed in emergency rooms where physician time is at a premium. Minutes shaved from a procedure, performed several times over the course of a shift, may result in the physician being able to tend to additional patients.